The spread of infectious disease resulting from the transfusion of contaminated blood or from the administration of contaminated blood products (e.g., plasma, blood factors, etc.) has been well documented and is recognized as a major public health concern. Most notably, the transmission of viral hepatitis and Acquired Immune Deficiency Syndrome (AIDS) through contaminated blood and blood products has received widespread attention. It is to be noted, however, that viral hepatitis and AIDS are only two of the many diseases that can be spread through the use of contaminated blood and blood products. Lesser known pathogenic viruses, such as T-cell lymphotropic viruses (Types I and II), cytomegalovirus, Epstein-Barr virus and the paroviruses, may also be spread through contaminated blood and blood products. In addition, still other pathogenic viruses that have not yet even been identified or recognized as being pathogenic infectious agents may be transmitted through contaminated blood and blood products and, therefore, similarly pose a serious public health risk. The HIV virus is illustrative of a virus that, until recently, was not even recognized as a pathogenic virus. Less than two decades ago, AIDS was not a recognized disease; today, there are over 10 million people worldwide who have contracted AIDS, many of these people having contracted the disease through the use of infected blood or blood products. Thus, it is clear that there is a great need for a method for effectively inactivating blood-borne infectious viruses.
In response to the aforementioned need, a number of techniques have been devised for inactivating infectious viral agents in blood and/or blood products. A review of many of these techniques is presented in Suomela, "Inactivation of Viruses in Blood and Plasma Products," Transfusion Medicine Reviews, Vol. VII, No. 1, pp. 42-57 (January 1993), which is incorporated herein by reference.
One such technique which has been used to inactivate viruses in blood and/or blood products is pasteurization. See e.g., Burnouf-Radosevich et al., "A Pasteurized Therapeutic Plasma," Infusionstherapie, 19:91-94 (1992), which is incorporated herein by reference. The pasteurization of blood and/or blood components is most often effected by heating them in the liquid state for 10 hours at 60.degree. C. A small amount of a protein stabilizer, such as caprylate or tryptophanate, is often added to the preparation. After pasteurization has been completed, the stabilizer typically must be removed from the preparation prior to its clinical use. As is the case with many of the viral inactivation techniques discussed herein, pasteurization is more effective in inactivating enveloped viruses (i.e., viruses having a lipid envelope surrounding the viral capsid) than in inactivating non-enveloped viruses (i.e., viruses which lack a lipid envelope surrounding the viral capsid).
Another technique which has been used to inactivate viruses in blood and/or blood products is the solvent/detergent (S/D) method. See e.g., Hellstern et al., "Manufacture and in vitro Characterization of a Solvent/Detergent-Treated Human Plasma," Vox Sang, 63:178-185 (1992); Horowitz et at., "Solvent/Detergent-Treated Plasma: A Virus-Inactivated Substitute for Fresh Frozen Plasma," Blood, 79(3):826-831 (Feb. 1, 1992); and Piquet et al., "Virus Inactivation of Fresh Frozen Plasma by a Solvent Detergent Procedure: Biological Results, Vox Sang, 63:251-256 (1992), all of which are incorporated herein by reference. The S/D method, which is limited too use in inactivating enveloped viruses, involves treating a blood preparation with an organic mixture which disrupts the lipid envelope of enveloped viruses. The disruption of the lipid envelope leads either to complete structural disruption of the virus or to destruction of the cell receptor recognition site on the virus. In either case, the virus is rendered noninfectious. The solvent used in the S/D method is most often tri-(n-butyl)phosphate (TNBP), and the detergent is either Tween 80, Triton X-100 or Na-cholate. Temperature and time influence the efficacy of the S/D method, typical temperatures being in the range of 24.degree. C. to 37.degree. C and the typical duration of treatment being at least 6 hours. As is the case with most additives used in viral inactivation techniques, the substances responsible for viral inactivation must be removed from the treated products before their clinical use.
Still another technique which has been used to inactivate viruses in blood and/or blood products is photochemical inactivation. See e.g., Mohr et al., "Virus Inactivated Single-Donor Fresh Plasma Preparations," Infusiontherapie, 19:79-83 (1992); Wagner et al., "Differential sensitivities of viruses in red cell suspensions to methylene blue photosensitization," Transfusion, 34(6) :521-526 (1994); Wagner et al., "Red cell alterations associated with virucidal methylene blue phototreatment," Transfusion, 33:30-36 (1993); Mohr et al., "No evidence for neoantigens in human plasma after photochemical virus inactivation," Ann. Hematol, 65:224-228 (1992); Lambrecht et al., "Photoinactivation of Viruses in Human Fresh Plasma by Phenothiazine Dyes in Combination with Visible Light," Vox Sang, 60:207-213 (1991), Goodrich et at., "Selective inactivation of viruses in the presence of human platelets: UV sensitization with psoralen derivatives, Proc. Natl. Acad. Sci. USA, 91:5552-5556(June 1994); Virus Inactivation in Plasma products, J.-J Morgenthaler, ed. Karger, N.Y. (1989); and BioWorld Today, Vol.4, No. 229, pages 1 and 4 (Nov. 24, 1993), all of which are incorporated herein by reference. The photochemical inactivation of a blood preparation typically involves treating the blood preparation with a photoactivatable chemical and then irradiating the preparation with light of a sufficient wavelength to activate the photoactivatable chemical. Examples of photoactivatable chemicals used in the photochemical inactivation of viruses present in blood preparations include psoralens, hypericin, methylene blue and toluidine blue. It is believed that psoralens, which have an affinity for nucleic acids, inactivate viruses by intercalating between viral nucleic acid base pairs and, in the presence of UVA light, forming a covalent bond with the viral nucleic acid, thereby preventing its transcription and/or replication. The manner in which hypericin, methylene blue and toluidine blue inactivate viruses is not as well-defined as that for psoralens. However, it is believed that these chemicals, when photoactivated, generate the highly reactive entity, singlet oxygen, which then attacks the cellular structure (e.g. viral envelope) of the virus.
Whereas photochemical inactivation has been largely successful in inactivating enveloped viruses, it has been largely unsuccessful in inactivating non-enveloped viruses. The failure of photochemical inactivation to inactivate non-enveloped viruses poses a significant public health problem since Poliovirus, Adenovirus, Hepatitis A and Parvovirus (Parvo B19) are among those non-enveloped viruses that are pathogenic to humans.
It should be noted that photochemical inactivation of the type described above has been most successful when applied to inactivating viruses in blood preparations lacking red blood cells (e.g., plasma). This is because blood preparations which include red blood cells typically absorb light at the same wavelengths used to photoactivate the chemicals.
Accordingly, there currently exists a need for a method for inactivating non-enveloped viruses, as well as enveloped viruses, in whole blood and/or blood products (e.g., plasma, platelets, blood factors, etc.).